Lockable implants and related methods

ABSTRACT

Total joint replacements for implants include a first member configured to attach to a first bone, a second member configured to reside in an adjacent second bone and a locking mechanism. The locking mechanism is configured to (i) lock the first and second members in alignment for full extension or other defined stabilized configuration and (ii) unlock to allow the first and second members to pivot relative to each other for flexion or bending.

RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 61/672,352, filed Jul. 17, 2012, the contents ofwhich are hereby incorporated by reference as if recited in full herein.

FIELD OF THE INVENTION

The present invention relates to surgical implants and is particularlysuitable for implants used in articulating joints and/or in the presenceof muscular deficiency.

BACKGROUND

Knee arthrodesis, indicated in the presence of inadequate muscularcontrol or soft tissue stability, allows for patients to successfullyambulate. This surgery results in a rigidly extended lower limb thatcannot be flexed or reduced in length. The extended position requiresgreater muscular strength and endurance to control, even when notmobile, which can lead to secondary joint pain and muscular fatigue. Thepermanence of this rigid extension can also prevent patientparticipation in many normal daily living activities such as bathing,tying shoes, or sitting in close quarter spaces such as a cars,airplanes and theaters.

Total knee replacement (TKR) is a surgical procedure to relieve pain,correct deformity, and restore knee function using artificial materialsto restore the load bearing and movement functions of the knee. Ifprimary treatment fails, a revision procedure is required. As the numberof knee replacement procedures increases, so does the incidence ofrevision surgeries. With each surgery more native anatomy is lost andthe risk of secondary damage to musculature, nerves and bone increases.Multiple surgical interventions can compound these risks and negativecomplications, and can lead to terminal knee dysfunction.

Other joints that may be suitable for implants can have similar or otherissues.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention provide lockable implants thatallow for flexion when desired by the patient, and that lock into afixed or semi-rigid configuration for structurally stable alternativeconfigurations.

The lockable implants can be selectively locked and/or unlocked by auser.

The lockable implants can have mechanical or electromechanical locks tolock and unlock the implant, and thus the associated lower anatomicalmember, into a specific orientation.

The lockable implants can include a magnetically operated lock thatcooperates with an externally applied magnetic field to lock and unlockthe implant.

The lockable implants can be self-locking, responsive to applying aforce at or above a defined force or load.

The lockable implants can include buttons, latches or flexible surfaceson the implant that are accessible by the user (through palpation or thelike) either manually or with a tool, that can be used to activate thelocking or unlocking ability of the implant.

Embodiments of the invention are directed to implants that include: (a)a first member configured to attach to a first bone; (b) a second memberin cooperating alignment with the first member configured to reside in asecond adjacent bone; and (c) a lock mechanism in communication with thefirst and/or second members configured to (i) lock the first member tothe second member for a stabilized configuration and (ii) unlock thefirst and second members to allow them to pivot relative to each otherfor flexion or bending.

The lock mechanism can be selectively actuated by a user to lock andunlock the implant.

The implant may include a hinge assembly having an axle configured tohingedly attach the first member to the second member. The hingeassembly can include a yoke with an axle channel that holds the axle andat least one spaced apart second channel. The lock mechanism can includeat least one locking member that selectively slides in defined forwardand reverse directions in the at least one second channel torespectively lock and unlock the first and second members.

The implant can include a hinge assembly having an axle configured tohingedly attach the first member to the second member. The hingeassembly can include a yoke that resides between the first and secondmembers and has a laterally extending yoke axle channel and at least onespaced apart laterally extending second channel that is spaced apartfrom the axle channel. The second member can include outer laterallyextending locking channels that reside on opposing ends of and can alignwith the at least one second laterally extending second channel. Thelock mechanism can include at least one locking member that can slide,side-to-side, through the second member locking channels to enter andexit a defined interior space of the at least one second channel of theyoke to lock and unlock the implant.

The second member can include spaced apart laterally extending axlechannels that reside on opposing ends of and can align with thelaterally extending axle channel so that the axle resides in the secondmember axle channels and the yoke axle channel.

The first member can have a bearing surface defined by a polymer insertthat holds the yoke and allows the second member to rotate in a flexionaxis relative to the first member.

The lock mechanism can include a magnet that slides to lock and/orunlock in response to application of an external magnetic field.

The lock mechanism can be configured to be manually selectively actuatedupon a contact force associated with a user physically pressing on anactuation member in communication with the lock mechanism that residesunder skin of the patient with the implant.

The implant can include a hinge assembly that attaches the first andsecond members. The hinge assembly can include a yoke with a channelthat receives first and second laterally spaced apart first and secondmagnets. The first or second member can include spaced apart openinterior spaces that align with opposing sides of the yoke, one thatreceives a first magnet and one that receives the second magnet. Thefirst and second magnets can slide out of the yoke channel into therespective first or second member interior spaces to unlock the lockmechanism and the magnets can slide into the yoke interior space to lockthe implant.

The lock mechanism can be self-engaging in response to application of aload introduced by the patient when the first and second members are ina substantially aligned orientation.

The implant can be a total joint replacement implant.

The implant can be a total knee replacement implant.

The implant can be a total joint replacement implant of an elbow.

Other embodiments are directed to methods of operating an implant in apatient. The methods include: (a) selectively unlocking a lock of animplant having first and second members using an implantable lockonboard the implant; and (b) selectively locking the lock to lock thefirst member and the second member together in a fixed configuration forstructural stability using the onboard lock.

The lock can include at least one magnet that slides and the selectivelylocking and unlocking can be carried out by passing an external magneticfield over the at least one magnet.

The selectively locking can be manually carried out by physicallypressing on an actuation member in communication with the lock thatresides under skin of the patient with the implant.

Other embodiments are directed to lockable implants. The implantsinclude a first member configured to attach to a first bone; a secondmember in cooperating alignment with the first member configured toreside in a second adjacent bone; and a lock mechanism in communicationwith the first and second members configured to (i) lock the firstmember to the second member for a stabilized configuration and (ii)unlock the first and second members to allow them to pivot relative toeach other for flexion or bending.

The lock mechanism can be selectively actuated by a user to lock andunlock the implant.

The lock mechanism can include at least one magnet that slides to lockand/or unlock in response to application of an external magnetic field.

The lock mechanism can be configured to be manually selectively actuatedupon a contact force associated with a user physically pressing on anactuation member in communication with the lock mechanism that residesunder skin of the patient with the implant.

The implant first and second members can have a cooperating ball andsocket configuration and the lock mechanism can include at least onelocking member that can slide through a locking channel to enter andexit a defined interior space of the first and/or second member to lockand unlock the implant.

The implant first and second members can be attached with a hinge havingan axle in an axle channel.

The implant can be a total hip replacement implant.

The lock mechanism can be self-engaging in response to application of aload introduced by the patient when the first and second members are ina substantially aligned and/or defined orientation.

The implant can be a total knee replacement implant.

The implant can be a total joint replacement implant.

The implant can be a total joint replacement implant of a wrist.

The implant can be a total joint replacement implant of a hip.

The implant can be a total joint replacement implant of a shoulder.

The implant can be a total joint replacement implant of an elbow.

The implant can be a total joint replacement implant of an ankle.

The selectively locking can be manually carried out by physicallypressing on an actuation member in communication with the lock thatresides under skin of the patient with the implant.

It is noted that aspects of the invention described with respect to oneembodiment, may be incorporated in a different embodiment although notspecifically described relative thereto. That is, all embodiments and/orfeatures of any embodiment can be combined in any way and/orcombination. Applicant reserves the right to change any originally filedclaim or file any new claim accordingly, including the right to be ableto amend any originally filed claim to depend from and/or incorporateany feature of any other claim although not originally claimed in thatmanner. These and other objects and/or aspects of the present inventionare explained in detail in the specification set forth below.

Other systems and/or methods according to embodiments of the inventionwill be or become apparent to one with skill in the art upon review ofthe following drawings and detailed description. It is intended that allsuch additional systems, methods, and/or devices be included within thisdescription, be within the scope of the present invention, and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of the present invention will be more readily understoodfrom the following detailed description of exemplary embodiments thereofwhen read in conjunction with the accompanying drawings.

FIG. 1 is an isometric perspective view of a knee implant according toembodiments of the present invention. The device is unlocked andpartially flexed.

FIG. 2 is an exploded view of the device shown in FIG. 1.

FIG. 3 is a side view of the device shown in FIG. 1. The device may belocked in this position.

FIG. 4 is a side view of the device shown in FIG. 1 in a partiallyflexed orientation. The device is unlocked.

FIG. 5 is a side view of the device shown in FIG. 1 and FIG. 3, withcomponents of the locking mechanism removed.

FIG. 6 is a side view of the device shown in FIG. 1 and FIG. 4 in apartially flexed orientation, with components of the locking mechanismremoved.

FIG. 7 is a sectioned midplane side view of the device shown in FIG. 1.The device may be locked or unlocked in this position.

FIG. 8 is a sectioned midplane side view of the device shown in FIG. 1in a partially flexed orientation. The device is unlocked.

FIG. 9 is an isometric view of the device shown in FIG. 1, andaligned/rotated about its flexion axis as shown in FIG. 3, FIG. 5, andFIG. 7. The device is in an unlocked state, and the femoral component isremoved for visibility.

FIG. 10 is an isometric view of the device shown in FIG. 1, andaligned/rotated about its flexion axis as shown in FIG. 3, FIG. 5, FIG.7, and FIG. 9. The device is in a locked state, and the femoralcomponent is removed for visibility.

FIG. 11 is a rear view of the device shown in FIG. 1, sectioned in afrontal plane across the center of the locking mechanism. The device isin an unlocked state.

FIG. 12 is a rear view of the device shown in FIG. 1, sectioned in afrontal plane across the center of the locking mechanism, as shown inFIG. 11. The device is in a locked state.

FIG. 13 is an isometric view of the device shown in FIG. 1, and rotatedabout its flexion axis as shown in FIG. 1, FIG. 2, FIG. 4, FIG. 6, andFIG. 8. The femoral component is removed for visibility. The device isunlocked.

FIG. 14 is an example of a knee implant system in position relative tothe femur “F” and tibia “T”.

FIG. 15 an example of an embodiment of the device with a mechanicalpushbutton for the locking mechanism according to embodiments of thepresent invention.

FIG. 16 is front view of the embodiment of the device seen in FIG. 15.

FIG. 16 is an embodiment of the device where the lock can occurvertically through the stem of the femoral and tibial componentsaccording to embodiments of the present invention, shown in the lockedposition.

FIG. 18 is a view of the embodiment shown in FIG. 17, in a flexed andunlocked position.

FIG. 19 is an embodiment of the device with another lock mechanism thatis configured with a latch that engages when the device moved into fullextension and/or a walking stable configuration according to yet otherembodiments of the present invention.

FIG. 20 is a side section view of the embodiment in FIG. 19.

FIG. 21 is a schematic illustration of an exemplary lockable implant inan elbow joint according to embodiments of the present invention.

FIG. 22 is a schematic illustration of an exemplary lockable totalreplacement hip implant according to embodiments of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, thethickness of certain lines, layers, components, elements or features maybe exaggerated for clarity. Broken lines illustrate optional features oroperations unless specified otherwise. One or more features shown anddiscussed with respect to one embodiment may be included in anotherembodiment even if not explicitly described or shown with anotherembodiment.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. As used herein, phrases such as “between X and Y” and“between about X and Y” should be interpreted to include X and Y. Asused herein, phrases such as “between about X and Y” mean “between aboutX and about Y.” As used herein, phrases such as “from about X to Y” mean“from about X to about Y.”

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

It will be understood that when an element is referred to as being “on”,“attached” to, “connected” to, “coupled” with, “contacting”, etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on”, “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” another feature may have portions thatoverlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention. The sequence of operations (orsteps) is not limited to the order presented in the claims or figuresunless specifically indicated otherwise.

The term “about” means that the recited number or value can vary by+/−20%.

The term “sterile” means that the noted device or material meets orexceeds defined medical guidelines of cleanliness and is substantially(if not totally) without contaminants so as to be suitable for medicaluses.

Turning now to the figures, FIG. 1 illustrates an example of a lockableimplant 10 that is a total knee replacement (TKR) implant 10 accordingto embodiments of the present invention. Although primarily described asa TKR, the implant 10 can be used in other joints, particularlyarticulating joints such as, for example, ankles, hips, shoulders,elbows, wrists and the like (see, e.g., FIG. 21). Although, the kneeimplant 10 can lock into place at about 0 and about 180 degrees, otherimplants can have other or additional locking orientations. For example,the elbow implant 10 (FIG. 21) can be configured to “lock” in place atabout 90 degrees.

Although the implant 10 is shown primarily herein as including a hingeto allow pivoting movement between two attached cooperating members 20,30, other attachment configurations for other movement of a particularjoint can be used, such as a ball and socket type configuration (FIG.22).

As shown, the implant 10 includes a first member 20, e.g., lower(tibial) member a second member 30, e.g., upper (femoral) member 30 witha lock or locking mechanism 40 (also called a latch). The lower member20 can be attached to the tibia (“T”) and the upper member 30 can beattached to the femur (“F”) via respective stems 25, 35. The lower andupper members 20, 30 can be connected via a hinge yoke 22. The lockingmechanism 40 can be incorporated into the hinge that is attached to therotating platform area using the hinge yoke 22.

The hinge yoke 22 can include a laterally extending channel or aperture122 ₂ that is aligned with channel 130 ₁ in the upper member 30 to holdan axle 50, typically inside an axle bearing 51, so as to allow theupper member 30 to pivot with respect to the lower member 20 via theaxle 50. The hinge yoke 22 can include a second channel or laterallyextending aperture 122 ₁ that holds a moveable locking member 52, shownas a pin or bolt, that can selectively slide to engage or disengage achannel 130 ₂ in the upper member 30 to (i) lock into a fullstabilization walking configuration (e.g., full extension) to allow anarthrodesis gait without requiring normal muscular strength and/orcontrol and (ii) unlock to allow the members 20, 30 to pivot relative toeach other for flexion or bending when not ambulating. FIG. 14illustrates an exemplary implant 10 in position relative to the femur“F” and the tibia “T”.

In some embodiments, the hinge yoke 22 can include first and secondspaced apart, laterally extending apertures or channels 122 ₁, 122 ₂(FIGS. 7, 9), one of which hold the axle 50 as discussed above and theother holding at least one slidable locking member 52. As shown, theaxle 50 may be larger than the locking member(s) 52, but the reverseconfiguration may also be used. The axle 50 can reside behind thelocking member(s) 52 as shown. In other embodiments, the axle 50 residesin front of the locking member(s) 52.

In the embodiment shown, at least one slidable locking member 52includes two locking members, one on each side of the implant 10. Thelocking members 52 can slide inward and outward substantially inconcert, or be separately deployable.

The hinge yoke locking member(s) channel 122 ₁ can be configured as asingle channel with a constant diameter or with different diameters.Where more than one locking member 52 is used, the different lockingmembers 52 can have different sizes (e.g., diameters) and/orconfigurations or may have the same configurations and sizes. In theembodiment shown, the hinge yoke 22 includes a forward channel 122 ₁with a reduced diameter or inner extending lip 57 at a medial sectionthereof 57 (FIGS. 11, 12) or with two aligned laterally extending closedchannels (not shown), one for each of the two locking members 52 (wheretwo are used). Although shown as two locking members 52 a single lockingmember 52 or more than two may be used.

In some embodiments, the implant 10 can include a polymer insert 21forming part of the hinge/rotating platform 121 as in conventionalimplants 10. The locking mechanism 40 can be incorporated intoconventional or novel hinge/rotating platform systems.

In some embodiments, the insert 21 and/or hinge yoke 22 can be providedin multiple configurations that can be selected by a doctor for aparticular patient so that the doctor can choose one that locks thepatient's leg 5-10 degrees short of “full extension” for a stablewalking configuration.

The implants 10 can be modular, interfacing with other implantablecomponents of a knee replacement system, allowing for adjustment of limblength and fixation angle. The implants 10 can be suitable for patientswho could undergo revision, but are at risk of complications that couldcompromise its success. The implants 10 can be used for patients withpoorly performing revision implants, but who do not desire permanentfusion (or amputation). The implants 10 can be used for patients thatotherwise would require fusion or amputation. The implants 10 can beused with patients having existing fusions who can “take-down” to thelockable knee implant to provide them with increased mobility or qualityof life. The implants 10 may also be used as a primary implant for afirst TKR surgery irrespective of whether a patient may have thecompromised tissue or bone structure as a precaution.

The implants 10 can have a hinge/rotating platform 121 and provideindustry standard stability. The locking configurations can beconfigured to fit modular revision TKRs. The interfacing configurationsof modular revision TKR implants can allow mix and match of componentsto custom fit to individual patients. The implant 10 can restore theknee joint function using a rotating hinge-like function with two axisof articulation, including articulating members 21, 30, which rotateabout axle 50, and articulating members 20 and 21, 22 which rotate aboutthe stem 23 (FIG. 7) of the hinge yoke 22, to allow the joint tofunction in a more normal fashion. In some embodiments, the implant 10can include a mobile, bearing-type sliding component that supports theyoke 22 and may allow for some Anterior/Posterior (AP) motion (notshown). For descriptions of conventional TKR designs, includingrotating, hinged designs, see, e.g., U.S. Pat. No. 5,358,527, U.S. Pat.No. 5,800,552, U.S. Pat. No. 7,572,292, U.S. Pat. No. 7,753,960, U.S.Pat. No. 7,799,084, and US PUB 2010/0131070, the contents of which arehereby incorporated by reference as if recited in full herein.

FIGS. 1 and 4 illustrate the implant 10 with the upper member 30partially pivoted relative to the lower member 20 allowing flexion. FIG.3 illustrates the implant 10 in a locked upright configuration forstable, weight-bearing walking.

The device 10 can be locked via mechanical or electromechanical lockingmechanism 40 that engages the hinge comprising the hinge yoke 22. Thelock or locking mechanism 40 is typically unpowered, but may bepassively powered (e.g., inductively powered) without requiring an onboard power source. The lock can be selectively activated and/ordeactivated by a user. The locking mechanism 40 can be manually orelectronically activated and/or deactivated. The locking mechanism 40can be manually actuated.

A user can activate and/or deactivate the locking mechanism from onestate to the other. The device 10 can maintain its current status untilthe user intervenes.

The locking mechanism 40 may be self-activating in response to a largeload, such as a load-bearing weight, being applied to the members 20,30, when the members 20, 30 are aligned in a substantially straight orother stable (walking) orientation (such that the pivot shaft of the twocomponents 20, 30, e.g., femoral and tibial components, aresubstantially in-line so that the limb is substantially straight). Thisactivation can be while a patient is prone on a bed or sofa by pushingagainst a foot board, for example, but is typically in response tostanding upright. The activation can be induced by a jolt, small jump orother movement to cause the mechanical lock to move to the lockorientation.

When members 22 and 30 are aligned as shown in FIG. 3, FIG. 5, FIG. 7,FIG. 9, FIG. 10, FIG. 11, and FIG. 12, each locking member 52 cantranslate axially within interior spaces 53, 54 of channels 122 ₁ and130 ₂ to lock and unlock the device 10. The lock is disengaged, as shownin FIGS. 9 and 11, when the locking members 52 reside entirely withinthe respective internal space 54 of channel 130 ₂ of member 30. The lockis engaged, as shown in FIGS. 10 and 12, when one or both lockingmembers 52 are in communication with the interior space 53 of channel122 ₁ of hinge yoke 22, blocking rotation of member 30 with respect tomember 22, and thus preventing flexion.

In some particular embodiments, an interruption 57 in the interiorchannel 122 ₁ that divides internal spaces 53 can take the form of areduced diameter, and can keep locking members 52 from physicallycontacting either other, or from traveling beyond a pre-determineddistance.

When the device 10 is rotated about axle 50, interference geometry 60 ofthe hinge yoke 22 blocks access of channel 122 ₁ and can serve to keeplocking members 52 from leaving interior space 54.

In some embodiments, as shown for example in FIG. 2, the lockingmechanism 40 can include a magnetic material 55, which can be a physical“permanent” magnet, that is embedded in, assembled, attached and/orconnected to the locking member 52. A cap 56 can be used to seal off themagnetic material 55 from bodily fluid. As shown in FIG. 2, the lockingmember 52 includes a receiving space that holds the magnetic material 55therein and cooperates with the cap 56 to seal the magnetic materialtherein.

With the use of an internal magnetic material 55, attractive orrepulsive axial (side-to-side relative to the implant body) force can beapplied to the bolts 52 with a user interface device 155 which can applyan external magnetic field (physical or electrical magnet via a userprobe, control or other user interface input device), causing thelocking member(s) 52 to translate laterally with respect to the implantbody 10.

In some embodiments, the polar axis of magnetic material 55 can bein-line with the axis of the lock, and external magnets in the samepolar axis can be passed over either side of the device 10, pulling thebolts medially and into an unlocked configuration as shown in FIG. 10and FIG. 12. By reversing the external magnets to the opposite polardirection, the user can pass the external magnets 155 m over either sideof the device 10 to move the locking members 52 medially to unlock thedevice 10 as shown in FIG. 9 and FIG. 11.

FIG. 14 illustrates that a tattoo or other externally visible marker 255can be applied to the skin of a patient over the locking mechanism 10 toprovide alignment information for directional reference for “lock” and“unlock” actions (which can be icons or other suitable visible indicia).

In some particular embodiments, the magnetic material 55 can be a rareearth magnet, which is typically much stronger than ferrous magnets.There are two conventional types of rare earth magnets, neodymiummagnets (e.g., neodymium-iron-boron) and samarium-cobalt magnets.

In some embodiments, the polar magnetic axis of magnetic material 55within locking members 52 can be aligned in such a way that the naturalstate of the implant is to remain locked until user intervention.

Magnetic material can be extremely brittle and can also be vulnerable tocorrosion (such as from the digestive acids in the body). The magneticmaterial can be sealed within the locking member 52 and cap 56. Themagnetic material 55 can be alternatively or additionally plated orcoated with a biocompatible material such as polyethylene to protectthem from breaking, chipping and/or for corrosion resistance. Particularexamples of rare earth magnets include Nd₂Fe₁₄B, SmCo₅ andSm(Co,Fe,Cu,Zr).

The magnetic material 55 can include a material that moves or changesviscosity in response to exposure to a magnetic field such as amagnetorheological fluid (also known as an MR fluid, available from LordCorporation, Erie, Pa.) or a ferrofluid. The fluids change viscositywhen subjected to a magnetic field.

The lock 40 can also or alternatively be a mechanical lock 58, as seenin FIG. 15, that can be manually pushed by a user to engage and/ordisengage the locking members 52. For example, a user can push againstskin on one side of the implant 10 to slide a pin in a defineddirection, e.g., inward or up or down, a distance sufficient todisengage a lock feature that engages or disengages the locking members52. FIGS. 15 and 16 illustrate an exemplary manually deployable pushbutton 58 that a user can use to engage or disengage the lockingmechanism 40, e.g., to slide locking members 52.

In some embodiments, the hinge yoke 22 can include a set of stacked domeor belleview washers, springs or other biasing members that can bias themovement in one direction (to the unlocked or locked position).

The locking mechanism 40 can be self-activating in response toapplication of load bearing weights as noted above.

The locking mechanism 40 can be a mechanical assembly that includes aset of stacked dome or belleview washers, springs or other biasingmembers that compress when a defined load is applied and allow a lockingmember to translate in a defined direction, e.g., sideways or up or downto engage a mechanical lock retention feature associated with the hingeyoke 22.

As shown in FIGS. 17 and 18, the locking mechanism 40 can be configuredso that locking can occur with a vertical lock member 52′, which residesin a channel 330 within the femoral component 30. When the user movesthe leg into full extension, locking member 52′ can slide down into analigned channel 230 of tibial component 20. When locking member 52′ isin simultaneous communication with both channels 230, 330 flexion cannotoccur and the device 10 is thus locked, allowing for ambulation. Whenthe user wishes to unlock the device, the user can lift the leg so thatthe tibial member is above the femoral member, and the locking member52′ will return entirely to the shaft 330 of femoral member 30, thusunlocking the device and allowing for flexion.

In some embodiments of the device 10, the locking mechanism 40 isconfigured so that locking can occur in response to when the device ismoved into full extension, as shown in FIG. 19 and FIG. 20. The lock orlocking mechanism 40 can include an upwardly projecting member 45 thatis in communication with a spring or other resilient member 46 to biasthe member in one position, e.g., the member 45 can be spring-loaded.The upper femoral component 30 includes an interior wall 30 w. Theupwardly projecting member 45 has a lip 47 or other shaped feature witha geometry shaped to interface with and secure with a defined depressionin the femoral component 30 interior wall 30 w. In this embodiment, thelocking mechanism 40 can be disengaged through the previously describedmethod of magnetic operation and/or a mechanical push actuation, e.g.,via a push button a or other input.

In other embodiments, the locking mechanism can be activated using aninductively powered circuit/switch based on an externally appliedinductive power source.

FIG. 21 shows the implant 10 can be for an elbow that can lock intoplace at about 60-120 degrees, e.g., about 90 degrees, from the long orsubstantially axially aligned configuration of the stem members 25, 35.

FIG. 22 shows an alternate implant 10′ with a lock mechanism 40 that canlock a ball and socket configuration as the two cooperating members 20′,30′ of a total replacement hip joint. The lock mechanism 40 can includeat least one locking member 52 (e.g., a magnet or other configurationsuch as one or more of the components/configurations described above)that slides into an interior cavity 10 c of the first or second member20, 30 to latch or lock the two members together in a defined stableconfiguration. The at least one locking member 52 can also slide furtherin the same direction or in an opposing direction to unlatch or unlockthe implant (the two members 20, 30) and allow bending and/or flexion.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. The inventionshould therefore not be limited by the above described embodiment,method, and examples, but by all embodiments and methods within thescope and spirit of the invention as claimed.

That which is claimed:
 1. An implant, comprising: a first memberconfigured to attach to a first bone; a second member in cooperatingalignment with the first member configured to reside in a secondadjacent bone; and a lock mechanism in communication with the firstand/or second member configured to (i) lock the first member to thesecond member for a stabilized configuration and (ii) unlock the firstand second members to allow them to pivot relative to each other forflexion or bending.
 2. The implant of claim 1, wherein the lockmechanism is selectively actuated by a user to lock and unlock theimplant.
 3. The implant of claim 1, further comprising a hinge assemblyhaving an axle configured to hingedly attach the first member to thesecond member, wherein the hinge assembly comprises a yoke with an axlechannel that holds the axle and at least one spaced apart secondchannel, wherein the lock mechanism comprises at least one lockingmember that selectively slides in defined forward and reverse directionsin the at least one second channel to respectively lock and unlock thefirst and second members.
 4. The implant of claim 1, further comprisinga hinge assembly having an axle configured to hingedly attach the firstmember to the second member, wherein the hinge assembly comprises a yokethat resides between the first and second members and has a laterallyextending yoke axle channel and at least one spaced apart laterallyextending second channel that is spaced apart from the axle channel,wherein the second member comprises outer laterally extending lockingchannels that reside on opposing ends of and can align with the at leastone second laterally extending second channel, and wherein the lockmechanism comprises at least one locking member that can slide,side-to-side, through the second member locking channels to enter andexit a defined interior space of the at least one second channel of theyoke to lock and unlock the implant.
 5. The implant of claim 4, whereinthe second member comprises spaced apart laterally extending axlechannels that reside on opposing ends of and can align with thelaterally extending axle channel so that the axle resides in the secondmember axle channels and the yoke axle channel.
 6. The implant of claim3, wherein the first member has a bearing surface defined by a polymerinsert that holds the yoke and allows the second member to rotate in aflexion axis relative to the first member.
 7. The implant of claim 1,wherein the lock mechanism comprises a magnet that slides to lock and/orunlock in response to application of an external magnetic field.
 8. Theimplant of claim 1, wherein the lock mechanism is configured to bemanually selectively actuated upon a contact force associated with auser physically pressing on an actuation member in communication withthe lock mechanism that resides under skin of the patient with theimplant.
 9. The implant of claim 1, further comprising a hinge assemblythat attaches the first and second members, wherein the hinge assemblycomprises a yoke with a channel that receives first and second laterallyspaced apart first and second magnets, and wherein the first or secondmember comprises spaced apart open interior spaces that align withopposing sides of the yoke, one that receives a first magnet and onethat receives the second magnet, and wherein the first and secondmagnets slide out of the yoke channel into the respective first orsecond member interior spaces to unlock the lock mechanism and themagnets slide into the yoke interior space to lock the implant.
 10. Theimplant of claim 1, wherein the lock mechanism is self-engaging inresponse to application of a load introduced by the patient when thefirst and second members are in a substantially aligned orientation. 11.The implant of claim 1, wherein the implant is a total joint replacementimplant.
 12. The implant of claim 1, wherein the implant is a total kneereplacement implant.
 13. The implant of claim 1, wherein the implant isa total joint replacement implant of an elbow.
 14. A method of operatingan implant in a patient, comprising: selectively unlocking a lock of animplant having first and second members that can move relative to eachother using an implantable lock onboard the implant; and selectivelylocking the lock to lock the first member and the second member togetherin a fixed configuration for structural stability using the onboardlock.
 15. The method of claim 14, wherein the lock comprises at leastone magnet that slides, and wherein the selectively locking andunlocking are carried out by passing an external magnetic field over theat least one magnet.
 16. The method of claim 14, wherein the selectivelylocking is manually carried out by physically pressing on an actuationmember in communication with the lock that resides under skin of thepatient with the implant.
 17. A lockable implant, comprising: a firstmember configured to attach to a first bone; a second member incooperating alignment with the first member configured to reside in asecond adjacent bone; and a lock mechanism in communication with thefirst and second members configured to (i) lock the first member to thesecond member for a stabilized configuration and (ii) unlock the firstand second members to allow them to pivot relative to each other forflexion or bending.
 18. The implant of claim 17, wherein the lockmechanism is selectively actuated by a user to lock and unlock theimplant.
 19. The implant of claim 17, wherein the lock mechanismcomprises at least one magnet that slides to lock and/or unlock inresponse to application of an external magnetic field.
 20. The implantof claim 17, wherein the lock mechanism is configured to be manuallyselectively actuated upon a contact force associated with a userphysically pressing on an actuation member in communication with thelock mechanism that resides under skin of the patient with the implant.21. The implant of claim 17, wherein the implant first and secondmembers have a cooperating ball and socket configuration and the lockmechanism comprises at least one locking member that can slide through alocking channel to enter and exit a defined interior space of the firstand/or second member to lock and unlock the implant.
 22. The implant ofclaim 17, wherein the implant first and second members are attached witha hinge having an axle in an axle channel.
 23. The implant of claim 21,wherein the implant is a total hip replacement implant.